Because
the price elasticity of demand shows the responsiveness of quantity
demanded to a price change, assuming that other factors that influence
demand are unchanged, it reflects movements along
a demand curve. With a downward-sloping demand curve, price and
quantity demanded move in opposite directions, so the price elasticity
of demand is always negative. A positive percentage change in price
implies a negative percentage change in quantity demanded, and vice
versa. Sometimes you will see the absolute value of the price elasticity
measure reported. In essence, the minus sign is ignored because it is
expected that there will be a negative (inverse) relationship between
quantity demanded and price. In this text, however, we will retain the
minus sign in reporting price elasticity of demand and will say “the
absolute value of the price elasticity of demand” when that is what we
are describing.